The present invention relates to a communication network system, in particular, a next-generation communication network system that adopts unique routing processing.
In a conventional communication network system, since respective routers, which constitute an AS (Autonomous System) serving as a network having a certain operation policy, perform routing processing (route selection processing) in accordance with a routing protocol such as an RIP (Routing Information Protocol) or an OSPF (Open Shortest Path First), processing loads applied to the respective routers are large. As a result, an amount of route information (routing information) flowing in the network increases, and a load on the network side increases.
Here, the RIP adopts a routing processing method of distance vectors, in which routers adjacent to each other exchange route information one after another to thereby make it possible to collect and set route information of the entire network. This RIP applies to a small-scale network effectively. In addition, in the OSPF, the respective routers grasp a structure of the entire network to make it possible to select an optimum route from the viewpoint of this structure. This OSPF applies to a large-scale network effectively.
In the BGP-4 (Border Gateway Protocol Version 4) or the like serving as an inter-AS routing protocol applied to the conventional communication network system, since routing processing is performed according to the number of pieces of route information among ASs (the number of ASs), for example, in the case in which a line is thin (a bandwidth of a transmission path is narrow) or the ASs are physically distant from one another, the routing processing is not always appropriate.
The BGP-4 is a mechanism of route control in inter-provider communication in an internet backbone constituted by providers and the like connecting to one another. In this GBP-4, it is possible to avoid this inconvenience tentatively according to a setting for operating route information.